Question

If bromine atom is available in the form of, say, two isotopes 79 35 Br (49.7%) and 81 35 Br (50.3%), calculate the average atomic mass of bromine atom.

NCERT Class IX
Sciences - Exemplar Problems

Chapter 4. Structure of the Atom

Answer 1

Heya,

Here is the answer:-

Average atomic mass of bromine
= (79×49.7%) +(81×50.3%)
=79×49.7/100 + 81×50.3/100
=79×0.497+81×0.503
=39.263+40.743
=80.006u

hope it helps u..

Answer 2

H i !

= [79 × 49.7%] + [81 × 50.3%] 

=  79 ×$\frac{49.7}{100}$  + 81 × $\frac{50.3}{100}$

= 79 × 0.497 + 81 × 0.503

=  39.263 + 40.743

= 80.006 a.m.u 

Average atomic mass of bromine = 80.006 a.m.u